JP2002193253A - Jointed can body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain good appearance of a can body, assure a rustproof property, and avoid a lowering of productivity and an increase of manufacturing cost. SOLUTION: A jointed can body is composed of a cylindrical body 6 possessing a joint jointing ends of a metal plate and an outer surface covering film 14 adhered to the outer surface of the body 6 through an adhesive. A stepped gap 20 created on the joint 5 is not corrected by paints, but corrected at the outer surface of the body 6 by the adhesive 17 setting after flowing when the outer surface covering sheet 14 is adhered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joined can body in which a metal plate is formed into a cylindrical shape and its ends are joined.

[0002]

2. Description of the Related Art Conventionally, the body portion of a three-piece can can body is formed by previously printing on a surface of a large plate-shaped or band-shaped metal body which is to be the outer surface of a can body, or by pasting a printed film. A metal plate (usually called a blank) cut to the size of one can is formed into a cylindrical shape, and the ends of the metal plate are overlapped with each other and bonded using welding or synthetic resin It is manufactured by joining by such methods. None of the joints and the vicinity thereof are not printed in order to secure the joining force, and have a color changed by the color of the metal material or welding heat. On the other hand, in order to maintain good appearance and aesthetic appearance of the can in the product state, and to prevent rust at the joint, a colored or printed outer covering film is attached to the outer surface of the can body. Accordingly, there is a method of covering the outer surface of the joint. The method of coating such a can body joint with an outer surface coating film includes:
A method of manufacturing a can body by molding a metal plate having an outer surface coating film attached thereon into a cylindrical shape, and a method of manufacturing a can body by molding a metal plate into a cylindrical shape, and joining ends thereof. ,
There is a method of sticking an outer coating film to the outer surface of the can body.

An example of the former method is disclosed in Japanese Patent Laid-Open No. 5-69485.
Japanese Patent Application Laid-Open No. H10-147339 discloses an example of a welded can body described in Japanese Patent Application Laid-Open No. 10-147339 and manufactured by the latter method. In the method for manufacturing a welded can body described in Japanese Patent Application Laid-Open No. 5-69485, a synthetic resin film is attached to a metal plate while leaving exposed metal portions for welding at both ends of the metal plate. After turning back to the side opposite to the exposed metal part for welding, then forming a metal plate into a cylindrical shape and welding the exposed metal parts at both ends, the folded part of the synthetic resin film is inverted and joined The outer surface side of the portion is covered with a synthetic resin film, and the inverted portion of the synthetic resin film is pressed against the can body using an adhesive device. According to the method for manufacturing a welding can body described in JP-A-5-69485, when welding both ends of a metal plate, the synthetic resin film covering the joint is
It is said that it does not hinder the welding operation.

On the other hand, in a welding can body described in Japanese Patent Application Laid-Open No. 10-147339, after a metal plate is formed into a cylindrical shape and both ends are welded, a canopy and a bottom lid are tightly wound to form a can body. The weld can body to be formed. This welding can body is specifically, before the welding can body and the canopy and the bottom lid are wound, the joint of the can body is covered and corrected by clear paint from the outer surface side of the can body for rust prevention. At the same time, a printed synthetic resin film is attached to the outer peripheral surface of the can body via an adhesive layer, and both ends of the synthetic resin film are overlapped with each other at a position corresponding to the joint portion. .
According to the welding can body described in Japanese Patent Application Laid-Open No. H10-147339, it is possible to obtain a good appearance by covering the joint of the can body with corrected coverage with a printed synthetic resin film. It has been.

[0005]

However, in the method for manufacturing a welded can body described in Japanese Patent Application Laid-Open No. 5-69485, a step of folding back a synthetic resin film before welding both ends of a metal plate, and After welding both ends of the plate, a step of inverting the folded portion of the synthetic resin film, a step of pressing the inverted portion of the synthetic resin film against the can body, and the like are necessary, and both ends of the metal plate are joined together. In addition to the welding machine that welds the resin, a bonding device for a synthetic resin film is required. Therefore, there has been a problem that the number of manufacturing steps is increased and the productivity is reduced, and the capital investment is increased and the manufacturing cost is increased.

Further, in the welding can body described in Japanese Patent Application Laid-Open No. 10-147339, since the outer surface of the joint is corrected with a clear paint for rust prevention, the outer surface of the printed outer surface coating film is corrected. Separately from the coating step and the drying step, a clear paint application step and a drying step are required, and a drying facility for drying the clear paint is required. Therefore, there has been a problem that the number of manufacturing steps is increased and the productivity is reduced, and the capital investment is increased and the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and it is possible to maintain good appearance of a can body and to ensure rust prevention without specially correcting the covering of a joint. In addition, an object of the present invention is to provide a joined can body capable of suppressing a decrease in productivity and an increase in manufacturing cost.

[0008]

Means for Solving the Problems and Actions To achieve the above object, a first aspect of the present invention is to provide a cylindrical body having a joining portion formed by joining ends of a metal plate, and an outer surface of the body. And a printed outer surface covering film attached with an adhesive, and a top cover and a bottom cover are fixedly wound around both open ends of the body portion to form a can body. In the can body, a step portion is formed at the joint portion, and the step portion is not corrected by coating with a paint, and the adhesive solidified after flowing at the time of attaching the outer surface coating film is applied to the body portion. Is characterized in that the step portion is covered on the outer surface side.

According to the first aspect of the present invention, on the outer surface of the body,
The step portion is covered on the outer surface side of the body by the adhesive that has flowed when the printed outer surface covering film is applied and then solidified. Therefore, in the manufacturing process of the can body, in order to correct the coating on the outer surface side of the can body, a special process such as applying and drying a paint on the bonded portion, and special equipment for this process. It is not necessary to provide.

According to a second aspect of the present invention, in addition to the first aspect, a region including the joining portion on the inner surface side of the body portion is covered with a thermoplastic resin film. Things.

According to the second aspect of the present invention, in addition to the same effect as that of the first aspect of the present invention, a region including the joint on the inner surface side of the body is covered with a thermoplastic resin film. When attaching an outer coating film to the outer surface of the body, the thickness of the inner coating that is damaged by the mandrel inserted into the can body can be increased more easily than the paint. Since the thermoplastic resin film is used, the influence on the corrosion resistance can be reduced. In addition, those having no problem with environmental hormones such as bisphenol A can be used.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, a portion of the thermoplastic resin film covering the joining portion is formed of a tape-shaped resin film,
The width of the tape-shaped resin film in the circumferential direction of the body is set to 5 to 15 mm, and the thickness of the tape-shaped resin film is set to 12 to 45 μm, and the tape-shaped resin film is A first layer facing the joint portion, and a second layer superposed on the first layer and facing the inside of the body portion, wherein the first layer has a melting point of 175 to 225. ° C, the second layer has a melting point of 195 ° C to 255 ° C, and is made of biaxially oriented resin, and the melting point of the resin constituting the second layer composes the first layer. 15 to 60 ° C. higher than the melting point of the resin to be formed, and the thickness of the first layer is
The thickness is set to be more than 60% of the total thickness of the tape-shaped resin film.

According to the third aspect of the invention, in addition to the same effect as the second aspect of the invention, the tape-shaped resin film is
The melting point of the resin constituting the first layer facing the joint is lower than the melting point of the biaxially oriented second layer resin facing the inner side of the body, and the thickness of the first layer is a tape-like resin. Since the thickness is set to be more than 60% of the thickness of the entire film, the first layer is melted, and it is possible to completely cover the corners of the step portion on the inner surface side of the joining portion, and to form the first layer. Since the second layer having a higher melting point does not melt, the biaxial orientation is maintained as it is.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings. The joined can body of the present invention is a joined can body used for a three-piece can, and the manufacturing process of the joined can body will be described. First, tin-free steel-based steel sheet having a two-layer coating of metallic chromium and hydrated chromium oxide, tin-based steel sheet subjected to tin plating and chromate treatment, nickel plating and diffusion treatment, followed by thin tin plating and chromate treatment A coating layer (which will be described later) is formed on one surface (a surface that constitutes the inner surface of the can body) of an appropriate can-treated surface-treated steel plate such as an ultra-thin tin-plated steel plate, a nickel-plated steel plate subjected to nickel plating and chromate treatment, or the like. To form an inner surface coating layer).

When this coating layer is formed, the thickness is 0.1
There are a method of applying a paint to a large plate or a band-shaped steel plate of 6 to 0.23 mm, and a method of attaching a synthetic resin film to the band-shaped steel plate. When applying paint to steel plates,
A coating material such as an epoxy phenol is applied by a coating device such as a roller. When attaching a synthetic resin film to a steel sheet, a synthetic resin film such as polyethylene terephthalate is directly adhered or attached to the steel sheet via a thermosetting or thermoplastic adhesive. In addition, the coating layer formed on the steel sheet is formed so as to leave about 1.5 mm to 5.0 mm in a width of a region to be joined at both ends to be joined when manufacturing the joining can body. In this manner, the strip-shaped steel sheet on which the coating layer is formed is cut into a size corresponding to one can body, and the blank 1 shown in FIG. 2 is manufactured. In FIG. 2, an inner surface coating layer 2 is formed on one surface of a blank 1.

The blank 1 is conveyed to the next step, is formed into a cylindrical shape so that the inner surface coating layer 2 is on the inside, and ends 3 and 4 of the blank 1 are overlapped with each other.
The overlapping portions are joined to form a joint 5. As shown in FIG. 3, a method of forming the joint portion 5 includes a method of welding the ends 3 and 4 by electric resistance mash seam welding and a method of bonding the ends 3 and 4 with an adhesive. And the like. In addition, the cylindrical body 6 is manufactured in a state where the step portion 20 is formed at the joining portion 5. Thus, the cylindrical body 6 and the joined can body (hereinafter simply abbreviated as can body) 7 having the inner surface coating layer 2 provided on the inner peripheral surface except for the joint 5 of the body 6 are formed. Manufactured.

Next, a joining portion 5 is provided on the inner surface side of the can body 7.
Is formed to cover the inner surface. The width of the inner surface repair layer 8 in the circumferential direction of the body 6 is 5 from the viewpoint of coverage and workability.
It is set within a range of 15 mm to 15 mm. The inner surface repair layer 8 can be formed as a single layer or a composite layer. As a method for forming the inner surface repair layer 8 as a single layer, there are a method of applying a paint to the inner surface side of the body portion 6 and a method of applying the paint to the body portion 6. A method in which a tape-shaped resin film is attached to the inner surface side of the tape. When a paint is applied to the inner surface side of the body 6, it is desirable to use a curable synthetic resin such as a polyester-based or phenol-based paint, particularly a thermosetting synthetic resin.

On the other hand, when the tape-shaped resin film is stuck on the inner surface side of the body 6, the temperature of the region where the tape-shaped resin film is stuck on the inner surface of the body 6 is set to 1
After heating in the range of 50 to 220 ° C., a tape-shaped resin film is pressure-bonded to the area. As a method of attaching the tape-shaped resin film, the tape-shaped resin film may be made of a thermo-adhesive material, or an adhesive layer of a thermosetting resin may be provided on the tape-shaped resin film. As the tape-shaped resin film, for example, polyethylene terephthalate resin, polyester resin such as polybutylene terephthalate resin, copolymerized polyester resin such as copolymerization of polyethylene terephthalate and isophthalate acid, polypropylene resin, polycarbonate resin, polystyrene resin A transparent polymer resin alone selected from polyolefin resins, vinyl chloride resins, and the like, or a tape-like resin film made of a composite of the above resins is used. The thickness of the tape-shaped resin film attached to the inner surface side of the body 6 is set in the range of 10 to 40 μm from the viewpoint of coverage and workability.

On the other hand, when the tape-shaped resin film is formed of a composite layer, as shown in FIG. 4, the tape-shaped resin film is superposed on the first layer 9 facing the body 6 and the first layer 9. And a second layer 10 facing the inside A1 side of the body 6. The first layer 9 has a melting point of 175 to 2
The second layer 10 is made of a thermoplastic resin within a temperature range of 25 ° C.
Has a melting point in the range of 195 ° C. to 255 ° C. and is made of a biaxially oriented thermoplastic resin.

Further, the melting point of the thermoplastic resin forming the second layer 10 is higher than the melting point of the thermoplastic resin forming the first layer 9 by 15 to 60 ° C., more preferably 20 to 60 ° C. , The material of the first layer 9 and the material of the second layer 10 are selected. Furthermore, the thickness of the first layer 9 is
The thickness is set to exceed 60% of the total thickness of the tape-shaped resin film. After the tape-shaped resin film is pressure-bonded to the joint portion 5, post-heating is performed at a temperature higher than the melting point of the first layer 9 and lower than the melting point of the second layer 10. As the thermoplastic resin used here, for example,
A polyethylene resin, a modified polyethylene resin, a polypropylene resin, a modified polypropylene resin, and a polyolefin resin can be used. However, when a polyester resin such as polyethylene terephthalate resin is used as the inner surface coating layer 2, the first layer 9 is used. It is more preferable to use a polyester resin from the viewpoint of adhesion between the resins. Furthermore, the thickness of the inner surface repair layer 8 is set in the range of 12 to 45 μm, more preferably in the range of 15 to 40 μm in consideration of corrosion resistance and workability.

The step of attaching the printed outer surface coating material to the outer surface of the can body 7 on which the inner surface repair layer 8 has been formed as described above will be described with reference to FIGS. . In FIG. 5, reference numeral 11 denotes a sticking device. The sticking device 11 has a sticking drum 12 that rotates in a predetermined direction, and a rubber-like elastic layer 13 provided on the outer peripheral surface of the sticking drum 12. . Note that heating means (not shown) such as a heater is provided inside the attaching drum 12.

Then, on the outer peripheral surface of the rubber-like elastic body layer 13,
An outer coating film 14 to be attached to the outer peripheral surface of the can body 7 is held, and is heated within a temperature range of 60 to 80 ° C. by a heater inside the attaching drum 12. This outer surface coating film 14 has a thermoplastic resin film 15 cut to a length equal to or longer than the entire circumference of the can body 7 and a clear coat layer 16 formed on one surface of the thermoplastic resin film 15. ing. Examples of the thermoplastic resin film 15 include, for example, polyethylene terephthalate resin, homopolyester-based resin such as polybutylene terephthalate resin, copolymerized polyester-based resin formed by copolymerization of polyethylene terephthalate and isophthalate acid, polypropylene resin, polycarbonate resin, A transparent polymer resin alone selected from a polystyrene resin, a polyolefin resin, a vinyl chloride resin, or the like, or a thermoplastic resin film made of a mixture or composite of the above resins is used.

The surface of the thermoplastic resin film 15 opposite to the clear coat layer 16 is printed (not shown), and gravure printing or flexographic printing can be used as this printing. . From the viewpoint of design, it is preferable to use gravure printing that has clear image quality and high quality. As the ink used for printing, a polyurethane, a vinyl chloride-vinyl acetate copolymer or the like is used, and isocyanate or the like is added as a curing agent.

The clear coat layer 16 improves the slip property on the outer surface side of the thermoplastic resin film 15 and
This is to prevent damage. As the clear coat layer 16, for example, a material obtained by adding a curing agent such as an amino resin to a polyester resin, an epoxy resin, an epoxy-modified polyester resin acrylic resin, or the like is used. In addition, a well-known lubricant may be contained in the curing agent. Thermoplastic resin film 1 held by sticking drum 12
In 5, the length of the attaching drum 12 in the circumferential direction is set to be longer than the entire circumferential length of the can body 7 by about 0.5 to 3 mm, and the length of the thermoplastic resin film 15 in the width direction of the attaching drum 12 is set. Is higher than the height of the can body 7 by 0.
It is set to be 3 to 1 mm shorter.

On the printing surface side of the thermoplastic resin film 15, a thermosetting adhesive 17 is applied.
The adhesive 17 is made of polyester, polyurethane,
An epoxy-based, polyethylene-based adhesive with good fluidity. Here, the "adhesive with good fluidity"
It melts (becomes in a fluid state) near 100 ° C., starts to be bonded to the outer surface of the body 6 as a mating member in a temperature range of 110 to 130 ° C., and is completed in a temperature range of 180 to 200 ° C. It means adhesive. here,
The polyester-based adhesive is a condensate of a polybasic acid and a polyhydric alcohol.

Specific examples of such polybasic acids include aromatic polybasic acids such as phthalic acid, isophthalic acid and terephthalic acid; alicyclic polybasic acids such as dihydrophthalic acid and tetrahydrophthalic acid; succinic acid; Adipic acid, suberic acid,
Aliphatic polybasic acids such as azelaic acid, maleic acid, fumaric acid, unsaturated fatty acids such as itaconic acid, and dimer acids derived from unsaturated fatty acids, and the like.Examples of polyhydric alcohols include ethylene glycol, Diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, polybutylene glycol, 1,3-pentadiol, neopentyl glycol, 1,6-hexane Diol, cyclohexanediol and the like.

The polyurethane-based adhesive is a polyisocyanate alone or a mixture of a compound such as a polyol containing an active hydrogen which easily reacts with an isocyanate group. Specific examples of the polyisocyanate compound include ethylene diisocyanate and polyisocyanate. Aliphatic diisocyanates such as 1,6-hexamethylene isocyanate; alicyclic diisocyanates such as isophorone diisocyanate; and aromatic diisocyanates such as naphthalene diisocyanate. Polyol compounds include polyester polyol and polycarbonate polyol.

Examples of the epoxy adhesive include diglycidyl ethers of bisphenol A or F, and oligomers thereof, diglycidyl ester of orthophthalic acid, diglycidyl ester of isophthalic acid, and diglycidyl ester of terephthalic acid. Furthermore,
The adhesive used in this embodiment includes, for example, titanium dioxide, white pigments such as zinc white, yellow pigments such as zinc yellow, vermilion, red pigments such as red iron, blue pigments such as navy blue and cobalt blue depending on the purpose and purpose. And green pigments such as chrome green and green earth.

Further, in order to enhance the adhesion between the adhesive 17 and the metal base of the body 6, it is preferable to use a combination of two or more types of adhesive 17 as the adhesive. Further, the thickness of the adhesive 17 is set in a range of 1 to 10 μm. In particular, in order to improve the design of the appearance of the can in the product state, it is preferable to set the thickness of the adhesive 17 in the range of 5 to 7 μm.

On the other hand, the can body 7 is held by, for example, a shaft-shaped mandrel 21, and the can body 7 is held by the mandrel 21 heated by high-frequency induction heating or an electric heater. 220
Heated in the range of ° C. And as shown in FIG.
With the adhesive 17 facing the can body 7 side, one end 18 of the outer surface covering film 14 is pressed against the outer peripheral surface of the can body 7 and the attaching drum 12 is rotated counterclockwise in FIG. At that time, since the mandrel 21 is attached so as to be able to rotate, both the can body 7 and the mandrel 21 rotate clockwise in FIG. In the circumferential direction of the can body 7, the pressing start position of the one end 18 is closer to the front than the joint 5 (the right side in FIG. 5).

Here, the adhesive 17 in contact with the heated can body 7 is brought into a molten state, and at the same time, the adhesive 17 flows due to the pressing of the outer coating film 14 by the sticking drum 12, so that the adhesive 17 flows. When the adhesive 17 completely covers the corners of the step portion 20 of the joining portion, and when the temperature of the adhesive 17 reaches a temperature at which bonding is possible, the outer surface coating film 14 is formed.
And the outer surface of the can body 7 are adhered to each other, so that the outer surface covering film 14 is gradually separated from the attaching drum 12. And
With the rotation of the attaching drum 12, as shown in FIG.
The outer surface side of the joint 5 is covered with the outer surface covering film 14.

Further, the attachment of the outer coating film 14 to the can body 7 is continued, and as shown in FIG. 19 overlap with each other to form a wrap portion B1. Through the steps described above, the can body 7 having the outer surface coated film 14 attached to the outer surface is manufactured. Further, since the adhesive 17 is not completely solidified only by sticking the outer surface coating film 14 to the heated can body 7, the heat setting is performed in a temperature range of 180 to 230 ° C. at which the adhesive 17 is completely solidified after sticking. Do it.

In the embodiment shown in FIG. 1, in the circumferential direction of the can body 7, the joint portion 5 and the lap portion B1 are set at different phases (positions where the joint portion 5 and the lap portion B1 do not overlap). However, the joining portion 5 is included in the arrangement phase of the wrap portion B1 (the lap portion B1 and the joining portion 5 overlap).
As described above, the length of the thermoplastic resin film 15 or the pressing start position of the one end portion 18 can be set. More specifically, in the circumferential direction of the can body 7, the front end of the other end portion 19, which is superimposed on the outer surface of the outer surface coating film 14, is shifted in phase by 2 mm on both sides with respect to the joint 5. Can be positioned within the specified range. In addition, in order to improve the tightness with a can lid described later, the pressing start position of the one end portion 18 of the outer surface covering film 14 is set to the left side of the step portion 20 in FIG. Can be prevented from becoming too thick. Further, in order to reduce the gap between the outer surface covering film 14 and the joint portion 5, it is preferable that the pressing start position of the one end portion 18 is adjacent to the side surface of the step portion 20.

When the outer surface coating film 14 has a light color tone, particularly a white or yellow color,
Although it depends on the concealing property of the adhesive 17, there is a possibility that the joint portion 5 may be seen from the outer surface side of the outer surface coating film 14 by a user, which is not preferable in appearance. For this reason, in the circumferential direction of the can body 7, the outer surface covering film 15 and the joining portion 5 are joined so that the joining portion 5 is not located at the main part of the design of the printing applied to the outer surface covering film 14. It is desirable to position. As described above, when positioning the outer surface covering film 14 and the joining portion 5 in the circumferential direction of the can body 7, the outer circumferential surface of the can body 7 is attached before the outer surface covering film 14 is attached to the outer surface of the can body 7. In the direction, the position of the joint 5 may be optically detected, and the position of the joint 5 and the one end 18 of the outer surface covering film 14 may be determined based on the detection result.

An upper cover and a bottom cover are wound around the open ends of the can body 7 manufactured as described above to form a can body. In this embodiment, since the outer surface side of the can body 7 and the area including the joining portion 5 are covered with the adhesive 17 and the printed outer surface covering film 14,
The joining portion 5 is not easily seen from the outer surface side, and the appearance and design are improved. In addition, the joint 5 is formed on the outer surface of the can body 7 by retort treatment after forming the can body.
Can be prevented from rusting.

In the manufacturing process of the can body 7, the body 6
The adhesive 17 for attaching the outer surface covering film 14 to the outer surface of the joint 5 is melted and flows when it comes into contact with the pre-heated can body 7, and completely flows to the corner of the step 20 of the joint 5. Solidified after coating. In other words, can body 7
The step of affixing the outer surface covering film 14 to the outer surface also serves as a step of correcting the joint portion 5 with the adhesive 17. For this reason, in the manufacturing process of the can body 7, in order to cover the joint portion 5 on the outer surface side of the can body 7, a special process such as application and drying of a paint to the joint portion 5 and a special process for this process are performed. There is no need to provide equipment. Therefore, an increase in man-hours for manufacturing the can body 7 is suppressed, thereby improving productivity, and an increase in capital investment is suppressed, so that an increase in manufacturing cost can be suppressed.

Further, the outer surface covering film 14 pressed by the attaching drum 12 is pressed by the stepped portion 2 of the joining portion 5 when pressed.
In a state where there is no gap between the outer surface covering film 14 and the step portion 20, the adhesive 17 located on the side facing the can body 7 is completely bent to the corner of the step portion 20 with no gap between the outer surface coating film 14 and the step portion 20. Coated. Then, after the outer surface covering film 14 is attached, the outer surface covering film 14 which is curved in a shape along the step portion 20 until the adhesive 17 is completely solidified by the heat setting step, is linearly formed by its elastic force. When trying to return to the shape, the adhesive 17 causes cohesive failure and separates and adheres to the thermoplastic resin film 15 and the surface of the trunk portion 6 including the step portion 20 of the joint portion 5. In this way, even when the gap portion 22 is formed between the outer surface covering film 14 and the joining portion 5, the joining portion 5 on the outer surface side of the can body 7 is bonded to the corner of the step portion 20 by the adhesive 17. Since it is completely covered, the rust prevention of the stepped portion 20 is maintained.

According to this embodiment, the inner surface repair layer 8
When the paint is applied as the above, the number of heating of the can body 7 is reduced by simultaneously performing the drying step of the paint in the heating step of the can body 7 before the outer surface covering film 14 is applied or the heat setting step after the application. Thus, the inner surface repair layer 8 is suppressed from being affected by heat. For example, this makes it possible to suppress the elution of bisphenol A contained in the thermosetting epoxy phenol resin or the like used as the inner surface repair layer 8.

On the other hand, when the outer coating film 14 is attached, the inner coating layer 2 and the inner repair layer 8 of the can body 7 come into contact with the mandrel 21 holding the can body 7, so that the inner coating layer 2 and the inner repair layer If the thickness of 8 is thin, there is a possibility that scratches or tears may occur. Therefore, it is necessary to increase the thickness of the inner surface coating layer 2 and the inner surface repair layer 8, but it is difficult to apply a thick coating with a paint due to fluidity and the like. Therefore, by attaching a thermoplastic resin film whose thickness can be easily increased to the inner surface side of the can body 7, when attaching the outer surface covering film 14 to the can body 7,
It can withstand the damage received from the mandrel 21 inserted into the can body 7 (the adverse effect on the corrosion resistance and the like can be reduced). Furthermore, by making the inner surface coating layer 2 and the inner surface repairing layer 8 of the can body 7 free from problems related to environmental hormones such as bisphenol A, it is also effective as an environmental hormone countermeasure.

Further, according to this embodiment, the tape-shaped resin film covering the joining portion 5 from the inner side of the body portion 6 has a melting point of the thermoplastic resin constituting the first layer 9 facing the joining portion 5. Is lower than the melting point of the thermoplastic resin of the second layer 10 facing the inside A1 side of the body 6, so that when the tape-shaped resin film is attached and post-heating is performed, the first layer 9 is melted. And the second layer 10 is not melted and the biaxial orientation of the second layer 10 is maintained. Therefore, the gas barrier property of the tape-shaped resin film is not impaired, the permeation of oxygen and water vapor can be prevented, and the corrosion resistance is not impaired.

By setting the thickness of the first layer 9 to 60% or more of the total thickness of the tape-shaped resin film, it is possible to completely cover the corners of the step portion on the inner surface side of the joining portion 5. In addition, the generation of rust can be reliably prevented. Further, after the tape-shaped resin film is pressed, the post-heating step for melting the first layer 9 is performed simultaneously with the heating step of the can body 7 before the outer surface covering film 14 is attached or the heat setting step after the attachment. This can suppress an increase in the number of heating steps and heating equipment.

An experiment for confirming the operation and effect of this embodiment was performed as in the following Embodiments 1 and 2. Example 1 A phenolic resin paint is applied to one surface of a steel plate (a surface to be an inner surface of a can body) except for a region to be joined, and the other surface of the steel plate (an outer surface of a can body). After applying a size coat to the surface, the steel sheet is formed into a cylindrical shape, the ends are overlapped and welded to produce a can body, and the joint is thermoset of epoxy resin on the inner surface side of the can body Repaired with mold paint. Then, the mandrel heated by high-frequency induction heating was inserted into the can body, and after the temperature of the can body was heated to 160 ° C., the outer surface coating film was attached to the outer surface of the can body with a compression force of 2744 N. Heat setting was performed in an oven at 200 ° C. for 3 minutes. The outer surface coating film has a thickness of 1 μm made of an epoxy resin on one surface of a polyethylene terephthalate resin film having a thickness of 12 μm.
m, a thermosetting clear coat layer is formed, and on the other surface, a 3 μm-thick printed layer gravure-printed with a urethane-based ink, and a thickness formed of a polyester-based resin and an epoxy-based resin In this case, a thermosetting adhesive layer of 5 μm is formed.

Neck-in processing was applied to both open ends of the joint can body manufactured in this manner, and then a bottom cover was fixedly fastened to one open end of the can body to manufacture a can body with a bottom cover. . After filling the can body with the bottom lid with an appropriate amount of hot water at 80 ° C., the top lid is wound around the other open end of the can body and fixed.
Pressure sterilization was performed at 30 ° C. for 30 minutes. Then, the can body filled with warm water was left in a retort pot for 24 hours. Thereafter, the outer surface of the can body, in particular, the joint was visually checked for the presence or absence of rust, but no rust was generated.

Example 2 A phenolic resin paint was applied to one surface of the steel plate (the surface to be the inner surface of the can body) except for a region to be joined, and the other surface of the steel plate was left as a metal base. Then, the steel sheet was formed into a cylindrical shape, and its ends were overlapped and welded to produce a can body. An outer surface covering film was stuck on the outer surface of this can body under the same conditions as in Example 1, and after heat setting under the same conditions as in Example 1, the can body was manufactured in the same manner as in Example 1. did. This can body was filled with an appropriate amount of warm water at 80 ° C., and was subjected to pressure sterilization at 130 ° C. for 60 minutes in a retort kettle, and then the can body was left for one day. Thereafter, the joined portion of the can body was visually confirmed, but no rust was generated.

According to another experiment conducted by the present inventors, the melting point of the first layer 9 of the tape-like resin film covering the inner surface side of the joining portion 5 was determined to be suitable for temperature and retortability (during retort treatment). From the viewpoint of preventing film peeling and whitening), corrosion resistance and preventing wrinkling.
To 225 ° C., and the melting point of the second layer 10 is 195 from the viewpoint of retort properties and corrosion resistance.
To 255.degree. C. has been obtained. The difference between the melting points of the first layer 9 and the second layer 10 is preferably 15 ° C. or more, particularly preferably 20 ° C. or more, from the viewpoint of temperature suitability. From the viewpoint of reducing the shrinkage of the layer 10, data is obtained that the temperature is preferably 60 ° C. or lower.

Further, the overall thickness of the tape-shaped resin film depends on the step embedding property (complete coverage of the corners of the step part on the inner surface side of the joint part 5) and the workability (neck processing of the opening end of the body part 6). From the viewpoint of preventing cracking or peeling of the film at the time) and corrosion resistance, it is necessary to be thicker than 10 μm and thinner than 50 μm, preferably within the range of 12 to 45 μm, particularly preferably within the range of 15 to 40 μm. Data is obtained. Furthermore, the thickness of the first layer 9 is required to be 10 μm or more from the viewpoints of step embedding property, adhesion of the tape-shaped resin film to the joint portion 5 and corrosion resistance, and the entire thickness of the tape-shaped resin film. It has been obtained that the thickness is preferably more than 60% of the thickness.

This embodiment can also be applied to a can body in which the ends of the blank are joined to each other. That is, the butted ends may be joined in a state of being shifted without being completely coincident with each other to form a stepped portion. The present invention is also applicable to such a can body. Here, the correspondence between the structure of this embodiment and the structure of the present invention will be described. The blank 1 corresponds to the metal plate of the present invention, and the inner coating layer 2 and the inner repair layer 8 are the thermoplastic resin of the present invention. Equivalent to film.

[0048]

As described above, according to the first aspect of the present invention, the adhesive which has flowed when the outer surface covering film is adhered to the outer surface of the body is solidified by the adhesive which has been formed on the outer surface side of the body. The step portion is covered. For this reason, in the manufacturing process of the can body, it is not necessary to provide a special process such as a step of applying and drying a paint to the joint portion and special equipment in order to correct the coating on the outer surface side of the can body. Therefore, an increase in the number of man-hours for manufacturing the can body is suppressed and the productivity is improved, and an increase in capital investment is suppressed and an increase in the manufacturing cost can be suppressed. Further, even when the outer surface covering film is peeled off from the step portion of the joining portion, since a part of the adhesive remains in a state of being attached to the step portion, rust prevention of the step portion can be maintained.

According to the second aspect of the present invention, in addition to obtaining the same effects as the first aspect of the present invention, the inner surface of the body is covered with a thermoplastic resin film, so that the outer surface of the body is covered with the outer surface. It is possible to prevent the thermoplastic resin film from being damaged or torn when the covering film is applied, and to prevent corrosion of the trunk. It is also effective as an environmental hormone countermeasure.

According to the third aspect of the present invention, in addition to obtaining the same effects as the second aspect of the present invention, the tape-shaped resin film has a melting point of the resin constituting the first layer facing the joint,
It is lower than the melting point of the resin of the biaxially oriented second layer facing the inner side of the body, and the thickness of the first layer is set to a thickness exceeding 60% of the total thickness of the tape-shaped resin film. Because
Corrosion resistance on the inner surface side of the joint is improved.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a joined can body of the present invention in a radial direction of the joined can body.

FIG. 2 is a sectional view of a blank used for manufacturing the joined can body shown in FIG.

FIG. 3 is an overall cross-sectional view in the radial direction of a joined can body manufactured by molding the blank of FIG. 2 into a cylindrical shape and joining the ends thereof.

FIG. 4 is a cross-sectional view illustrating a configuration example of a tape-shaped resin film covering a bonding portion of the bonding can body illustrated in FIG.

FIG. 5 is a sectional view showing a manufacturing process of the joined can body shown in FIG. 1;

FIG. 6 is a sectional view showing a manufacturing process of the joined can body shown in FIG. 1;

[Explanation of symbols]

1 ... blank, 2 ... inner surface coating layer, points 3, 4 ... end,
Reference numeral 5: bonding portion, 6: body portion, 7: can body, 8: inner surface repair layer, 9: first layer, 10: second layer, 14: outer surface coating film, 17: adhesive, 20: step portion, A1
…internal.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Atsushi Kobayashi 5-5-1 Nishihashimoto, Sagamihara-shi, Kanagawa F-term in the Technical Development Center, Daiwa Seikan Co., Ltd. 3E061 AA16 AB13 AD01 BA04 BA07 DA02 DB01 DB04 DB06 3E062 AA04 AB01 AB07 AC03 BA20 BB06 DA01 DA02 DA09 JA01 JB04 JB23 JC02 JD01 JD03

Claims (3)

[Claims] 1. A tubular body having a joining portion in which ends of a metal plate are joined together, and an outer surface covering film which is attached to an outer surface of the body via an adhesive and printed. A joint can body for forming a can body by winding and fixing an upper lid and a bottom lid to both open ends of the body portion, wherein a step portion is formed in the joint portion, and the step portion is formed. The stepped portion is covered on the outer surface side of the body portion with the adhesive that has flowed when the outer surface covering film is adhered and has been solidified without being coated with the paint, and the stepped portion is covered. . 2. The joined can body according to claim 1, wherein a region including the joining portion on the inner surface side of the body portion is covered with a thermoplastic resin film. 3. A portion of the thermoplastic resin film which covers the joining portion is formed of a tape-shaped resin film, and a width of the tape-shaped resin film in a circumferential direction of the body is 5 to 15 mm. Is set, and
The thickness of the tape-shaped resin film is 12 to 45 μm
And the tape-shaped resin film has a first layer facing the joining portion, and a second layer superposed on the first layer and facing the inside of the body portion. The first layer has a melting point of 175 to 225 ° C., and the second layer has a melting point of 195 to 255 ° C. and is made of biaxially oriented resin. The melting point of the constituent resin is 15 to 60 ° C. higher than the melting point of the resin forming the first layer, and the thickness of the first layer is 60% of the total thickness of the tape-shaped resin film.
3. The joined can body according to claim 2, wherein the thickness is set to be greater than